Low voltage gas arc lamp



` Jam 21, 1936- K. F. J. KlRsTEN 2,028,548

Low VOLTAGE GAS ARC. LAMP Filed April 5, 1952 I Y l A ORNE.'

Patented Jan. 21, 1936 LOW VOLTAGE GAS ARC Kurt F. J. Kirsten, Seattle, Wash., assignor to Kirsten Lighting Corporation, a corporation of Washington Application April 5, 1932, Serial No. 603,245

5 Claims.

This invention relates to gas arc lamps, and more particularly to the formation of luminous arcs in rare gases such as helium, neon, crypton, xenon and mercury vapor, which arcs, after being once established, maintain themselves at a relatively low voltage and emit a light of great intensity and of a color characteristic of the gas or gases involved; it being the principal object of the present invention to improve upon the gas arc lamps set forth in my applications now pending, by the elimination of all external transformers, special circuits, and other costly and bulky equipment, and to make possible the operation of gaseous filament arc lamps directly on standard low voltage circuits in a manner that is practical for purposes of general illumination.

It is also an object of the present invention to provide a lamp of the above stated character, having an over all positive resistance characteristic, which makes it possible to operate the lamp in parallel with other lamps of a like construction; this being impossible in lamps of this type as disclosed in the prior art.

Another object of the invention resides in the utilizing of arc stabilizing resistance for heating the cathodes, and the embodiment of this resistance in the main circuit as distinguished from its being in an auxiliary circuit.

A still further object of this invention is to provide a lamp that may be used as a asher and without load uctuation on the power main and without serious sparking of the contacts of the control switch.

Other objects of the invention reside in the details of construction of the electrodes and in the construction and combination of the various parts associated therewith.

In accomplishing the various objects of the invention I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawing,

wherein- Fig. 1 is a view diagrammatically illustrating a. typical gas arc lamp unit as embodied by the present invention.

Fig. 2 is an enlarged longitudinal section of one o! the terminal electrodes.

Fig. 3 is a. cross sectional view, taken on line 3--3 in Fig. 2.

Fig. 4 is an enlarged, longitudinal section of the mounting spool for the cathode heating element used in the electrode.

Fig. 5 is an end view of the spool.

In my co-pending applications, above mentioned, relating to gas arc lamps and nled under Serial No. 499,253, Serial No. 580,400 and Serial No. 596,753, the fact was stated that all low voltage arcs are not stable since they have a negative resistance characteristic and, for this reason,

the arc current must be passed through a sta- 5 bilizing reactance or resistance. In the prior art lamps, of which I have knowledge, reactance or resistance for this purpose is provided in circuit connections external of the lamp; a reactance being preferable in order to minimize the energy loss which is always involved in a resistance carrying current. Also, in hot cathode lamps of the prior art, the energy for heating the cathodes is supplied by a special circuit or circuits from the circuit transformer. The present lamp is a departure from the prior art devices especially in the use and location of the arc stabilizing resistance, as will presently be apparent.

Referring more in detail to the drawing- I designates an air tight, tubular, transparent vessel provided at its opposite ends with tubular enlargements 2 and 2 containing the terminal electrodes designated generally by the reference characters A and B, each of which is like the other in construction and operation. Electrode A is provided with sealed-in terminal connections 3, 4 and 5. Likewise, electrode B is provided With corresponding sealed-in terminal connections 3', 4 and 5. The terminals 5 and 5 are connected externally of the tube by wires 6 and I which extend therefrom, respectively, t0 the opposite ends of a condenser 8. The terminals 3 and 3 likewise are connected externally of the tube by wires 9 and I0 through a resistance or reactance designated at I I, with a switch I2 interposed in the connection. The terminals 4 and 4 are connected, respectively, by Wires I3 and I4 with switch contacts I5 and I6 and a control switch Il is provided for making or breaking connection with the circuit mains I8 and I9.

Located within the terminal portions 2 and 2 of the tube I, as seen best in Fig. 2, are tubular, metallic sleeves 20 and 20. Each of these is connected electrically at its inner end by a cross Wire 2l with its corresponding connection 5 or 5. Located within the sleeves 20 and 20', respectively, are resistance elements 22 and 22 here shown in the form of spiral coils connected at their outer ends to their respective terminals 3 and 3' and at their other ends are connected electrically with metallic sheaths 23 and 23', within which they are mounted upon insulating spools 25. 'I'hese spools, as seen in Fig. 4, are spirally grooved as at 26 to receive the coils of the resistance elements and cross bars 21' of insulating material extend between the spool ends, overlying the windings to hold them in place. The metallic sheaths 23 and 23' preferably are coated with a. suitable metallic oxide to aid in stimulation of an arc within the lamp when electrical potential is impressed thereon. The sheaths 23 and 23 are connected electrically at their outer ends with their respective terminals 4 and d'. It will be mentioned here that the sleeves and 2li may be either in the form illustrated or may be of mesh construction. Also, they may be shorter in length and even assume the form of a wire band. However, the form shown is now preferred as it is a protection that prevents blackening of the tube surface incident to use of the lamp.

The resistance or reactance il should be oi such nature as to give a voltage drop equal to the voltage drop of the arc.

The operation of the lamp is as follows:

Assuming that switch l2 is closed, then when the switch il, connected with a standard low potential alternating current main, for instance one of one hundred twenty volts, is closed, a difference of potential is established between the parts 23 and 23' of the two electrodes; it being observed that these parts are connected externally of the lamp through the resistance elements 22 and 22', terminals 3 and 3', resistance or reactance il and switch l2. The magnitude of the current flowing through the connections, is equal to the voltage of the main divided by the sum of resistances 22 and 22 and li. As soon as the current flows through the resistance 22 and 22', heat is generated therein which in turn radiates to the oxide coated, metallic sheaths 23 and 23', which constitute the electrodes proper. The potential between these electrodes is equal to the voltage of the main minus the drop across the two resistances 22 and 22', or equal to the drop across the resistance l i. This voltage is not sumcient to kindle the arc, however, the electrodes are stimulated by the radiation of heat thereto from the heated resistance elements and by their oxide coating to function under what is known as "electronic emission, thus after the electrodes have been heated to a dull red, opening of switch l2 immediately raises the voltage of the main, which is suicient to kindle the arc between the electrodes. 'Ihis arc kindling voltage has been reduced to a practical minimum by the corona circuit provided by the sleeves '20-20 and their connections 6 and 'l through condenser 8. Thus, when 't electrodes become heated, a corona current w..... flow between them and their respective sleeves 2li-2U', and this ow of corona mwerfully stimulates electronic emission and thus the opening of switch l2 immediately raises the potential between the electrodes 23 and 23' to the full voltage of the main which is suiicient to kindle the arc in tubes of considerable length. The operation of this corona current is well explained in my prior applications, especially that of Serial No. 580,400.

As soon as the arc between the electrodes is thus established, the potential between the elements 23 and 23' falls to a value equal to the voltage of the main minus the resistance drop through coils 22 and 22', created by the arc current which must iiow through them before leaving the electrodes. The greater the arc current the greater is the resistance drop and consequently, the circuit as a whole is a stable circuit with a positive resistance characteristic if the value of the resistance 22 and 22' is such as to more than make up for the ohmic change of the arc path with a given increase in current in the arc path.

It may be preferred in some instances, especially when such lamps are used for purposes of general illumination, to use the resistance l l for temporary lighting during the period of heating the electrodes and forming the arc. To accomplish this, the resistance il or reactance would be replaced by an incandescent lamp as designated in dotted lines in Fig. 1, which would become i1 luminated immediately upon closing switch il but would cease to function upon opening of switch l2.

In order to more clearly describe the design and operation of the present invention, some actual performance data of an experimental unit will here be given:

A tube of twenty six mm. diameter and twenty inches long was filled with neon gas at a pressure of approximately seven mm. The circuit energizing the tube was as shown in Fig.` l. Upon closing switches l and i2, a current of two amperes flowed through the heating resistance 22 of the electrode. The metallic sheath 23 glowed red in a few seconds. Upon opening switch l2, an arc was formed between electrodes 23 and 23 and the arc current also measured two amperes. This shows that by the proper 'design of resistances 22--22 and il, the current through re sistances 222-22' is the same, whether switch i2 is open or closed. Since the voltage drop across resistance il is the same as across the arc path in the lamp, it is apparent that the opening or closing of switch i2 merely diverts the current from one path to the other without changing the current in the circuit as a whole.

This characteristic lends itself most strikingly to intermittent ashing of the lamp without load iluctuations on the power main and without serious sparking of the contacts of switch i2. Since the opening or closing of switch i2 does not change the current in elements 22 and 22', there is no tendency of loss of oxide from the electrodes 23-23', and hence long life of the lamp is assured. whether it burns steadily or whether its arc is ashed on and oi'r" rapidly during operation.

Furthermore, the over all positive resistance characteristic makes possible the use of this lamp in parallel with other lamps.

Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is 1. In combination a. sealed, gas containing vessel provided with sealed in terminal electrodes, connectors joining the electrodes, respectively, with opposite sides of an electric circuit through which electrical potential may be impressed on the elec trodes to establish an arc between them; said resistance elements connected to said circuit in shunt with the discharge path, resistance elements adjacent the electrodes adapted to become heated by the current ilow, thereby to heat the electrodes by radiation, and a corona current conductor extending from the close proximity of one electrode Within the vessel to close proximity of the other through which a corona current will be established incident to heating of the electrodes, thereby to stimulate electronic emission from the electrodes and the establishment of an arc between them.

2. In combination a sealed, gas containing vessel provided with sealed in terminal electrodes, a circuit having opposite sides connected with terminals of the electrodes through which electrical potential .may be impressed on the electrodes to maintain an arc between them, a corona current conductor extending from the close proximity of one electrode within the lamp to the close proximity of the other electrode; said circuit including therein a conductor joining the electrodes, resistance elements in series in the conductor and closely associated with the electrodes and adapted to be heated by iiow of current therein to heat the electrodes by radiation, thereby to stimulate electronic emission therefrom to the corona current conductor, and a switch in the conductor between the electrodes to be opened after establishment of the corona current thereby to cause formation of the arc in the lamp.

3. In combination, a sealed, transparent, gas containing Vessel with terminal electrodes sealed therein, a circuit leading in series through the electrodes and by which electrical potential may be impressed thereon to establish an arc within the vessel, a corona current conductor extending between the electrodes and having terminal portions extended about the electrodes within the vessel in spaced relation thereto; said circuit including resistance elements through which current will flow between the electrodes and which will be heated thereby to heat the electrodes as a means of stimulating electronic emission to the corona circuit terminals, and a circuit opening switch in the circuit connection between the electrodes.

4. In combination, a sealed transparent vessel formed with terminal electrodes, a corona current conductor having opposite ends disposed slightly spaced from the electrodes within the vessel, a circuit leading in series connection through the electrodes and including thereinin the connection between the electrodes, resistance elements to be heated by ow of current to heat the electrodes to stimulate electronic emission and corona flow through the corona conductor, the said circuit connection between the electrodes including a resistance having a voltage drop equal to the voltage drop of the arc, and a switch to be opened after establishment of the corona current.

5. A combination as in claim 4 wherein the corona current connection includes a condenser.

KURT F. J. KIRS'IEN. 

